1. Field of the Invention
The present invention relates to a sensor calibrator for multicomponent sensors.
2. Description of the Prior Art
There are multidegree of freedom force/moment sensor calibrators presently used, which are large structural frames with gravitational loads applied to calibrate the sensors. However, the accuracy is subject to variations and the calibrators are not portable.
A device that has a stand with adjustable end members for supporting a test piece, and a crosshead that can be used for inducing test signals is shown in U.S. Pat. No. 4,283,952. The test supports adjustably move toward and away from each other, and center under a crosshead. The test parts are stator blades that are excited by a member between the blades, and the supports each support an individual part which move toward each other. U.S. Pat. No. 2,957,342 shows a machine for measuring torque and tension, utilizing a test stand that has clamps for supporting a test threaded fastener, which is simultaneously tested under torque and tension.
A multipurpose test fixture is shown in U.S. Pat. No. 2,845,794. The fixture has provisions for self-alignment to compensate for setup or dimensional discrepancies. The fixture is designed for testing hooks and has the ability to prestress, tensile test and fatigue test standard specimens.
A large testing and checking device used for checking force measuring instruments is shown in U.S. Pat. No. 3,608,353. Various adjustments are shown for vertical positioning as well, but it does not test a sensor which measures multiple forces and moments.
A calibration device for strain measuring instruments is shown in U.S. Pat. No. 4,292,835. The device includes a loading frame having linear displacement transducers and force measuring apparatus to determine the stress and strain relationship of a bolt or stud. An ultrasonic extensometer strain measuring apparatus is also monitored, and is calibrated in accordance with the linear displacement and force measurement readings.
A device for calibrating torque transducers is shown in U.S. Pat. No. 4,543,814, and a high temperature strain gauge calibration fixture is shown in U.S. Pat. No. 3,956,919. The high temperature strain gauge calibration fixture calibrates high temperature strain gauges and has an arm which can be placed into a furnace for sensing.
A weighing structure with variable moment load cells is shown in U.S. Pat. No. 4,666,006. This device is primarily of general interest.
U.S. Pat. No. 2,357,643 illustrates a calibrating apparatus that has threaded members for applying loads and which is used for calibrating electrical resistance strain gauge units.
A load cell support is shown in U.S. Pat. No. 4,606,421, and this unit has a shift error adjuster for compensating for off-center loading, but does not show a calibration device for sensors.